1. Field of the Invention
The present invention relates to a speed change lever apparatus for use in a bicycle.
2. Description of the Related Arts
A conventional speed change lever apparatus is known, for example, from a Japanese laid-open patent No. 61-143275. This speed change lever apparatus includes a winding member for winding up a speed change control cable, the winding member being held in position by a frictional force, a single speed change lever for effecting a speed change operation, a pair of one-way mechanisms consisting of ratchet mechanisms arranged in opposition to each other between the speed change lever and the winding member, each ratchet mechanism having a projectable/retractable claw, and an urging means for urging the speed change lever back to an intermediate position between its forward and reverse strokes after the winding member is pivoted in a cable winding or cable rewinding direction by a forward or reverse operation of the speed change lever.
With the above-described conventional speed change lever apparatus, however, the speed change lever is operated in the two directions. Accordingly, for effecting a speed change operation, a cyclist must pay much of his attention to the direction of the lever operation. This is undesirable in terms of the cyclist's safety as well as speed change operation efficiency, because the speed change device will be operated into an unexpected speed position if the cyclist operates the lever in the wrong direction.
Further, in case the speed change lever apparatus is attached adjacent a grip portion of a steering handle bar of the bicycle and if the apparatus is to provide as many as five or six different speeds, the lever of the apparatus necessarily has a considerable operation stroke. This means that the cyclist needs to use two of his fingers, i.e. the thumb and index finger for a forward and reverse operation of the lever, respectively. As is well-known, the index finger contributes significantly to the handle gripping condition. Then, if this index finger has to move significantly away from the grip for a speed change operation as described above, this results in deterioration in the handle gripping condition, thereby to endanger the cyclist.
Moreover, in order to be operated not only by the cyclist's thumb but by the index finger, the speed change lever must be attached to an upper portion of the steering handle. As a result, for forwardly operating the lever, the cyclist must move his thumb clumsily upwards to the position of the lever, whereby the gripping condition can deteriorate in this case also, though may be less significant than the former case.
In view of the above-described state of the art, the primary object of the present invention is to provide such a speed change lever apparatus for use in a bicycle as permits a cyclist to carry out a speed change operation in a safe manner without losing much of his handle gripping force and also in a carefree manner without requiring much attention from the cyclist to the direction of the operation.